Evaporator for refrigerating machines



May 24, 1938. 1.. w; ATCHISON EVAPORATOR FOR REFRIGERATING MACHINESFiled March 5, 1956 n o :m 9 r e 3% 13m ew m vd 2 W O my 9 b PatentedMay 24, 193% ear curios EVAPORATOR FOR EEFEIGERATING MACHINES 1 LeonardW. Atchison, Schenectady, N. Y., assignor to General Electricil'iompany, a corporation of New York Application March 5,

t Claims.

My invention relates to evaporators oi the flooded type forrefrigerating machines.

Evaporators of the flooded type for refrigerating machines are commonlyprovided with a header in which the liquid and gaseous refrigerant areseparated and from which the gaseous refrigerant is withdrawn. Some orthe lubricant which is utilized to lubricate the working parts of therefrigerant compressor is unavoidably carried with the refrigerant intothe evaporator. It is necessary to provide some arrangement forreturning the lubricant to the compressor in order to prevent a largeaccumulation of lubricant in the evaporator which would interfere withits operation by reducing vaporization of refrigerant and deplete thesupply of lubricant available for lubricating the working parts.

When the lubricant and liquid refrigerant form an intimate mixture notseparable by gravity, it

is necessary to withdraw small amounts of the mixture from the header ofthe evaporator and heat this portion of the mixture to evaporate therefrigerant and separate it from the lubricant. When the lubricantandliquid refrigerant are separable by gravity they may be separatedwithin the evaporator by providing an undisturbed zone of liquid thereinfrom the top of which the lubricant may be withdrawn with the aseousrefrigerant; this prevents slugs of liquid refrigerant from entering thecompressor with possible damage to the parts thereof; v

It is an object of my invention to provide a flooded evaporator forrefrigerating machines having an improved arrangement for separatingliquid refrigerant and lubricant, and for withdrawing the lubricant iromthe evaporator.

Another object of my invention is to provide a flooded evaporator forrefrigerating machines which is constructed of sheets of metal securedtogether and having indentations formed therein to provide a header,refrigerant circulating passages communicating with the header and alubricant separating device between the header and. the suction line.

A further object of my invention is to provide a flooded evaporator forrefrigerating machines including a header and refrigerant circulatingpassages and having an arrangement for separating liquid refrigerant andlubricant which is operable whether the liquid refrigerant and lu-'1936, @erial No. W269 which characterize my invention will be pointedout with particularity in the claims annexed to and forming a part ofthis specification.

For a better understanding of my invention reference may be had to theaccompanying drawing, in which Fig. l is a front elevation of ahousehold refrigerating machine provided with an evaporator embodying myinvention; Fig. 2 is an enlarged perspective rear view of the evaporatorshowh in Fig. l; and Fig. 3 is an enlarged side elevation, partly insection, of a portion of the evaporator shown in Fig. 2.

Referring now to Fig. l, l have shown a household refrigerating machineincluding a thermally insulated cabinet it having a door it and providedwith a thermally insulated top l2 on which is mounted a refrigeratingmachine. The refrigerating machine includes a closed casing IS in whichis arranged a motor and a compressor, an air cooled condenser I4surrounding the cas ing It and having a condenser conduit it formedtherein, a liquid receiver or float valve chamber l6 and a U-shapedflooded evaporator II supported from the top l2 within the cabinet l0.

cabinet ill and the vaporized refrigerant is withdrawn through a suctionline i9 and returned to the compressor within the casing l3.- Within thecasing I3 is provided a body of a liquid lubricant, such as highlyrefined mineral oil, which is circulated about the working parts of themotor and the compressor to lubricate them. Some of this lubricant isunavoidably entrained in the refrigerant discharged in the compressorand finds its way through the, condenser and float chamber to theevaporator H. In order to prevent the accumulation of the lubricantwithin the evaporator II, it is necessary to provide some arrangementfor separating the lubricant and refrigerant and for returning thelubricant to the compressor casing. The evaporator I1, is, therefore,provided with a lubricant separating chamber in which the lubricant andrefrigerant are permitted to separate either by, gravity or by heatingand which is so arranged that the lubricant alone will flow toward thesuction line and will be withdrawn from the evaporator with the gaseousrefrigerant, the liquid refrigerant in the separating chamber beingevaporated before it can reach the suction line.

The construction of the evaporator and lubricant separating chamber isclearly shown in Figs. 2 and 3. The evaporator I1 is constructed ofinner and outer metal sheets 20 and 2|, respectively, secured togetherabout their edges by welding or in any other suitable manner, the edgeof the sheet 20 being bent around the edge of the sheet 2|, as indicatedat 22. The sheets 20 and 2! are bent in U-shaped form to provide theside and bottom walls of a freezing chamber. Therefrigerant passagewaysof the evaporator are formed by indentations in the sheets 20 and 2 I,and the sheets 20 and 2| are secured together by welding, brazing, or inany other suitable manner between the indentations in order to providefurther strength. The two sides of the evaporator are of identicalconstruction, each side being provided with a header 23 partially filledwith liquid refrigerant wherein liquid and gaseous refrigerant areseparated, and a plurality of refrigerant circulating conduits 24 areprovided to connect the headers 23 and permit the circulation of liquidrefrigerant about the walls of the evaporator.

The conduits 24 extend below the level of liquid refrigerant in theheaders 23, so that the conduits are flooded with liquid refrigerant.Above the headers 23 are provided passages or chambers 25 communicatingat one end with the headers 23 through an upright connection 26 and attheir other ends remote from the header connection with a crossconnection 21 to which the suction line I9 is connected. The passages 25are inclined from the connection 26 toward the cross connection 21 andare provided on their lower sides with a plurality of pockets 28, whichare arranged to trap liquid refrigerant and lubricant at successivelylower levels along the passage between the header and suction line, asclearly shown in Fig. 3.

trapped in the pockets 28 at the bottom of the passage 25. The pockets28 at the end of the passage 25 near the. connection 26 are deeper thanthose at the other end and the pockets are so arranged that each onewill overflow into the adjacent pocket nearer the suction line and,consequently, the liquid will move toward thesuction line as more liquidis added to the pockets 23' near the connection 26. If the mixture ofliquid refrigerant and lubricant'in the pockets 2! is separable bygravity the lubricant will settle out on top of the refrigerant in thepockets and, consequently, the lubricant tends to overflow from onepocket to the next while the refrigerant remains in the pockets at thebottom where it is vaporized by the absorption of heat from the walls ofthe evaporator and is then withdrawn through During the operation of theevaporator l| liquid refrigerant and lubricant are admitted the suctionline IS with the gaseous refrigerant. Liquid refrigerant, therefore,will not reach the last pocket 28 and only lubricant will be withdrawnthrough the suction line. If the mixture of liquid refrigerant andlubricant is not separable by gravity there results, nevertheless, a

separation of the refrigerant and lubricant in the pockets 28 since thepockets 28 hold the mixture so that it can absorb heat from the walls ofthe evaporator and, consequently, refrigerant is continuously vaporizedfrom the mixture; the mixture in the succeeding pockets as it flowstoward the suction line contains less and less liquid refrigerant. Byproviding a sufficient length of the passage 25. and a sufficient numberof the pockets 28 the separation of liquid refrigerant and lubricant maybe "accomplished within the pockets so that lubricant alone reaches thelast pocket and is withdrawn through the suction line. a

It is readily apparent from the foregoing that I have provided a floodedevaporator for refrigerating machines having arranged therein a simpleand effective device for separating liquid refrigerant and lubricantwhether the mixture of liquid refrigerant and lubricant be separable bygravity or not.

While I have shown and described my invention in connection with aflooded evaporator for household refrigerating machines, otherapplications will readily be apparent to those skilled in the art. I donot, therefore, desire my invention to be limited to the particularconstruction shown and described and I intend in the appended claims tocover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A flooded evaporator for refrigerating machines including sheets ofmetal secured together and having a header formed therebetween forseparating liquid and gaseous refrigerant, a refrigerant circulatingconduit formed between said sheets and communicating with said header,means for admitting liquid refrigerant and lubricant to said conduit,means including a suction line for withdrawing gaseous refrigerant fromsaid evaporator, and means including a passage formed between saidsheets above said header for providing communication between said headerand said suction line, said last-mentioned means including a pluralityof pockets communicating with. said passage for facilitating theseparation of liquid refrigerant and lubricant to prevent the withdrawal'of slugs of liquid refrigerant through said suction line.,,.

2. A flooded evaporator for refrigerating machines including sheets ofmetal secured together and having a header formed therebetween forseparating liquid and gaseous refrigerant, a plurality of refrigerantcirculating conduits formed between said sheets and communicating withsaid header, means for admitting to said conduits liquid refrigerant andlubricant, means including a suction line for withdrawing gaseousrefrigerant from said evaporator, means including a passage formedbetween said sheets and communicating-at one end with said header and atthe other end with said suction line for removing gaseous refrigerantand lubricant from said header, and means including a plurality ofpockets formed between said sheets in said passage for trapping liquidrefrigerant and lubricant and for facilitating the separation of theliquid refrigerant and lubricant to prevent the withdrawal 2,118,687 7of slugs of liquid refrigerant through said suction line.

3. A flooded evaporator for refrigerating machines including sheets ofmetal secured together and having a header formed therebetween forseparating liquid and gaseous refrigerant, a plurality of refrigerantcirculating conduits formed between said sheets and communicating withsaid header, means for admitting to said conduits liquid refrigerant andlubricant, means including a suction line for withdrawing refrigerantfrom said evaporator, means including a passage formed between saidsheets and communicating atone end with said header and at the other endwith said suction line for removing gaseous refrigerant and lubricantfrom said header, and means including a plurality of pockets formedbetween said sheets and arranged to trap liquid at successively lowerlevels in said passage between said header and said suction line and tocause the liquid in said pockets to overflow from one pocket to anothertoward said suction line for facilitating the separation of liquidrefrigerant and lubricant.

l. An evaporator oi the flooded type for refrigerating machinesincluding complementary U-shaped sheet metal portions forming a plural--ity of walls of a freezing chamber, a header formed between said sheetmetal portions in each leg of said evaporator, a plurality ofrefrigerant circulating conduits formed between said sheet metalportions and connecting said headers, means for admitting liquidrefrigerant and lubricant to said conduits, means including a passageformed between said sheet metal portions in each of the legs of, saidevaporator and extending substantially parallel to and above saidheaders for removing gaseous refrigerant and lubricant from saidheaders, means including a suction line connecting said passages remotefrom said headers for removing gaseous refrigerant and lubricant fromsaid evaporator, and means including a plurality of pockets arranged insaid passages for trapping liquid refrigerant and lubricant and forfacilitating the separation oi the liquid refrigerant and lubricant toprevent the withdrawal of slugs of liquid refrigerant through saidsuction line. 7

LEONARD W. ATCI'HSON.

